1. Field of the Invention
The present invention relates to the apparatus and a method for insulating, sealing and protecting the joint of two insulated cables which are butt-spliced together.
2. Description of the Prior Art
Splices in electrically insulated cables, particularly those cables used in a distribution network, must be electrically insulated, protected from the elements and protected from physical damage which may be caused by digging, rocks and animals. The means utilized to protect the splice must be electrically nonconductive, must provide a seal to the cable insulation adjacent the splice to provide protection from the elements, should be resistant to abrasion and cutting and should be easily applied so that the splice protection may be applied in the field.
A number of methods have been described for accomplishing one or more of the desirable requirements of a protective device for a cable splice. U.S. Pat. No. 3,122,597, for example, describes a method of sealing splices in insulated electrical cables in which a mold is placed around the splice and filled with epoxy resin. Since the epoxy does not normally adhere well to the material used to insulate the cable, o-rings compatible with the epoxy are placed over the cable insulation prior to molding. These rings provide a seal from the elements and the epoxy coating provides resistance to damage. The primary drawback of such a system is that the protective epoxy coating cannot be easily applied in the field.
U.S. Pat. No. 3,268,654 discloses a rubber sleeve which spans the splice and is sealed to the cable insulation by means of band clamps. Although this structure is effective in sealing the splice from the elements and is easily applied, little protection from physical damage is afforded.
U.S. Pat. No. 3,515,798 describes a highly stretched rubber sleeve which is supported by a spirally-grooved core. After placing the core and sleeve assembly over the splice, the core may be unwound and removed to permit the sleeve to contract and seal the joint area. Such a structure is very easy to apply and highly effective in sealing the splice from the elements, but does not achieve the degree of physical protection which is considered desirable.
Finally, U.S. Pat. No. 2,958,722 describes a structure which utilizes o-rings encircling the insulation at either side of the splice which are covered by a rubber sleeve which spans the joint area. The structure of this patent effectively seals the splice from the elements, but affords little protection from physical damage. In addition, U.S. Pat. No. 2,958,722 suggests that the o-rings should be sufficiently tight fitting as to actually bite into the insulation of the cables and that the rubber sleeve "should have a diameter substantially equal to or slightly less than the diameter of the electric cables 1 and 2, so that it fits tightly about the insulated sections 5 and 6 of the wires and holds in contact by frictional engagement." It is apparent that these tight fitting o-rings and sleeve would be very difficult to apply in the field, and U.S. Pat. No. 2,958,722 suggests no method by which such application might be accomplished.